51131449991 has 2 divisors, whose sum is σ = 51131449992. Its totient is φ = 51131449990.

The previous prime is 51131449987. The next prime is 51131450093. The reversal of 51131449991 is 19994413115.

It is a happy number.

51131449991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 51131449991 - 2² = 51131449987 is a prime.

It is a super-2 number, since 2×51131449991² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51131449981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25565724995 + 25565724996.

It is an arithmetic number, because the mean of its divisors is an integer number (25565724996).

Almost surely, 2^51131449991 is an apocalyptic number.

51131449991 is a deficient number, since it is larger than the sum of its proper divisors (1).

51131449991 is an equidigital number, since it uses as much as digits as its factorization.

51131449991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 174960, while the sum is 47.

The spelling of 51131449991 in words is "fifty-one billion, one hundred thirty-one million, four hundred forty-nine thousand, nine hundred ninety-one".